One way that I have found to easily identify resin-coated papers (which were introduced in 1968) is to run the back of your fingernail along the back of the photo (think of it as a light scrape) and then look at the test area in reflected light. If it's RC paper, you can typically see a difference in the reflectivity of the "scrape" line vs the area around it. (I know I know, but it sounds a lot more destructive than it actually is). If it's not resin-coated (in other words, the back is just uncoated paper), you won't see any difference in reflectivity (unless you have greasy fingernails I guess).
Vince, I might also add that if the photo is in any way not what you expected, you may certainly return it for a full refund. In looking back at my description (which was written quite some time ago), I see a few details that I would have stated differently to avoid any confusion if I were writing up the same photo today. I'm just not in the habit of revisiting every item I have listed each time I tweak my typical auction write-ups
